The overall aim of this project is to produce a radioantibody preparation to carcinoembryonic antigen (CEA) which would permit the localization of tumors producing this antigenic substance by photoscanning techniques. This will be accomplished by utilizing the GW-39 human colonic carcinoma transplants which synthesize CEA. This tumor has been growing continuously at various sites of unconditioned golden hamsters, and will serve as the primary model for radiolocalization studies. BIBLIOGRAPHIC REFERENCES: D.M. Goldenberg: Oncofetal and Other Tumor-Associated Antigens of the Human Digestive System. In : Current Topics in Pathology, V. 63, Pathology of the Gastro-intestina Tract (Ed.: B.C. Morson), Springer-Verlag, Berlin-Heidelberg, 1976, pp. 290-342.